Speaking in the House of Representatives, Mr Obama told his audience that his generation's task was "to reignite the true engine of America's economic growth - a rising, thriving middle class".

'North Star'

"We have cleared away the rubble of crisis, and we can say with renewed confidence that the state of our union is strong,'' Mr Obama said in an hour-long address.

Those hoping for a more conciliatory tone than this notably aggressive State of the Union speech were disappointed

By Mark MardellNorth America editor

Delivering growth and jobs will be the "North Star that guides our efforts", he added.

But he insisted that nothing he planned would raise the deficit "by a single dime".

Mr Obama proposed reforms to reduce the cost of Medicare, a federal healthcare programme for pensioners, but argued "we can't just cut our way to prosperity".

In his speech, Mr Obama went on to call for federal investment in infrastructure, clean energy and education.

And he vowed to act on climate change himself if Congress failed to enact legislation.

"I urge this Congress to pursue a bipartisan, market-based solution to climate change...," he said.

"But if Congress won't act sooner to protect future generations, I will. I will direct my cabinet to come up with executive actions we can take, now and in the future, to reduce pollution, prepare our communities for the consequences of climate change, and speed the transition to more sustainable sources of energy."

Mr Obama also said he would reduce by more than half the number of US troops in Afghanistan over the next year.

He asked Congress to raise the minimum wage $7.25 to $9 an hour, called for legislation to ensure women are paid equally to men and announced a commission to improve the voting process.

On gun control, Mr Obama said an "overwhelming" majority of Americans supported "common-sense reform" on firearms, including tighter background checks and restrictions on "weapons of war and massive ammunition magazines".

And he urged gun-control opponents to allow a vote in Congress on his proposals.

"The families of Oak Creek, and Tucson, and Blacksburg, and the countless other communities ripped open by gun violence - they deserve a simple vote," he said.

Conservative divisions

He also praised bipartisan efforts to draw up an immigration reform bill, adding that if he is sent legislation, "I will sign it right away".

House Speaker John Boehner told US media on Wednesday said that immigration was the only issue on Mr Obama's state of the union list that had any chance in Congress this year.

He added he believed the president was more interested in getting a Democratic majority in both chambers of Congress in the 2014 mid-term elections.

Less than a day after North Korea tested a nuclear device, Mr Obama said the US will "lead the world in taking firm action in response to these threats".

Mr Obama will take to the road in the coming days to push his economic recovery proposals, stopping in the US states of North Carolina and Georgia and in his hometown of Chicago, Illinois.

But Senate Minority Leader Mitch McConnell, a Republican, was not impressed by what he called "pedestrian liberal boilerplate".

"An opportunity to bring together the country instead became another retread of lip service and liberalism,'' he said on Wednesday.

US media reaction

The New York Times says Mr Obama "continued trying to define a 21st Century version of liberalism that could outlast his time in office and do for Democrats what Reagan did for Republicans".

Part of that liberalism, the Washington Post says, included Mr Obama's call to "pivot away from the politics of austerity".

Politico called it an "aggressive speech with an even more aggressive message" and says that for the "Republican lawmakers who complain that [President Obama has] been too rough on them already - he's just getting started".

On Senator Marco Rubio's Republican response, Real Clear Politics says he delivered an effective "call for conservatives to govern by their principles and also an appeal to voters who have soured on the GOP in recent years, asking that they give the party another look".